in

in which on which at which的区别：in which可以翻译成在……里面；on which可以翻译成在……的上面，或具体时间的某一天；at which可以翻译成在……里面或在……

关系副词与“介词+which”的区别

引导定语从句时where与in which有时可互换，有时不能互换，注意以下几点：

当“介词+ which”在定语从句中作时间、地点和原因状语时，可以用相应的关系副词when, where和why来替换。

1. when根据情况可以等于in which, at which, on which等。如：

The day when (=on which) she arrived was Thursday. 她到的那天是星期四。

2. where根据情况可以等于in which, at which, on which等。如：

This is the hotel where ( =in which / at which) they were staying. 这就是他们当时住的旅店。

3. 关系副词若要换成“介词+which”只能是for which。如：

The reason why (=for which) I came here was to be with my family. 我到这里来的原因是要跟我的家里人在一起。